dirstate: better error messages when dirstate is corrupted
The current error message "Overflow in dirstate" sounds confusing
because it suggests either a certain size limit that's being exceeded,
or integer arithmetic overflowing. The reality is just a file being shorter
than expected.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}